12V DC Light Dimmer Circuit Using 555 Timer IC

12V DC Light Dimmer Circuit Using 555 Timer IC

This is a 12 volt at 2 amp Lamp dimmer that can be used to dim a standard 25 watt bulb by controlling the duty cycle of a astable 555 timer oscillator.

PARTS LIST

R1

1KΩ

R2

1KΩ

R3

100Ω 2W

VR1

50KΩ Preset

C1

0.1µF (104)

C2

470µF 25V

D1

1N4001

Q1

BC140

Q2

2N2955

LAMP1

12V Light

When the potentiometer is at the up position, the capacitor will charge quickly through both 1k resistors and the diode, producing a short positive interval and long negative interval which dims the lamp to near darkness.

555 Timer IC PIN Configuration

When the potentiometer is at the lower position, the capacitor will charge through both 1k resistors and the 50k potentiometer and discharge through the lower 1k resistor, producing a long positive interval and short negative interval which brightens the lamp to near full intensity.

BC140 PIN Configuration

The duty cycle of the 200Hz square wave can be varied from approximately 5% to 95%.

You can drive more power light using 2 or more parallel 2n2955 transistors with good heat sink.

is it possible to have a digital potentiometer instead of VR1?
I’m designing a dimmer switch which can be controlled wireless. So I have a decoder. So basically what I want is to connect the decoder, timer and the digital pot to the dimmer switch..